Ixvi FISHES OF ILLINOIS 



tion of 740 feet, but it descends within 4 miles to 700 feet, to 

 650 feet in the next 2^ miles, and to 600 feet 12 miles below. 

 Another descent of 100 feet is made in the following 31 miles, 

 while at a point 42 miles below this the 400 feet contour- line is 

 crossed. The mouth of the stream, 104 miles distant, lies 323 

 feet above tide. Thus the total descent of the river is 317 

 feet, giving an average fall of about 1.7 feet per mile. 



In the first 40 to 50 miles the main stream is largely inde- 

 pendent of preglacial lines, and there is consequently little val- 

 ley. The remainder of its course, however, is determined by 

 a broad preglacial valley except for a short distance below 

 Carmi, where it cuts across a projecting spur of hills leading in 

 from the west. This valley, like others in this region, has been 

 filled in its lower course with drift and alluvium to a level perhaps 

 100 feet above the rock bottom (Leverett). It is from an 

 eighth to a fourth of a mile wide in Effingham county, but 

 below, reaches a width of one to three miles. At times the 

 river is bordered locally by precipitous bluffs 40 to 50 or even 

 100 feet in height, while at other points there is a gradually 

 sloping surface from the bottoms up to the level of the adjacent 

 prairie. The river-bottoms are a rich, sandy loam, but are 

 valued little for agriculture on account of the overflow to which 

 they are subject during the annual spring freshets. They are, 

 however, valued for the heavy timber which covers them. 



The most important tributary of the Little Wabash is 

 Skillet Fork which enters from the west near Carmi. The 

 length of this stream is about 78 miles, not including the wind- 

 ings of its course, and it has a watershed of nearly 1,080 square 

 miles. It rises in northeast Marion county and flows south 

 and then southeast. Its source is at an elevation of 600 feet, but 

 it has a fall of 100 feet in its first 6 miles and makes another 

 descent of 50 feet in the next 12 miles. During the rest of its 

 course it falls but 100 feet. In the upper, swifter section the 

 precipitous bluffs rise to a height of 60 to 75 feet, and there is 

 little valley; but in the lower part the stream occupies a pre- 

 glacial valley similar to that occupied by the Little Wabash. 



SALINE RIVER SYSTEM 



The Saline River system drains into the Ohio that portion of 

 southeastern Illinois which lies immediately north of the Ozark 

 ridge. Its basin covers an area of about 2,000 square miles. 



